Horizontal Gene Transfer in Plants using Agrobacterium
Introduction Agrobacterium is a genus of gram-negative bacteria which induces tumor formation in plants through horizontal gene transfer. The most commonly studied species within the genus is Agrobacterium tumefaciens, which is well known for it ability to transfer DNA between itself and plants. Due to this ability the genus of Agrobacterium has become important in the genetic engineering of plants, but more specifically agricultural products. Some of the plants that have been genetically modified in the US using Agrobacterium are: * Soybeans * Cotton * Corn * Sugar Beet * Alfalfa * Wheat * Rapeseed Oil (Canola) * Creeping Bentgrass * Rice (Golden Rice) Agrobacterium in Nature A study was done examining 36 different species of plants in nature for the presence of the Transfer-DNA of A. rhizogenes ''and ''A. tumefaciens that found 2 species of plants infected contained the same homologous sequences. These included rolB, rolC, ORF13, ORF14, and the mis genes. These genes were seen as a single tandem imperfect repeat within the genome of the plants, and acted similarly to a retrotransposon. The expression of these genes was also negative, which means the insertion site is most likely silent. This suggests that the infection of plant species in nature is rare. Agrobacterium Horizontal Gene Transfer in the Creation of GMOs Using restriction enzymes and transformation a gene of interest (i.e. atrazine metabolism) with its promoter, is placed within a plasmid of the agrobacterium. Specifically the gene must have a promoter and erminatorr on each end. Then the plasmid must be inserted into the nucleus of the plant. This culture is then used to infect a population of plants (i.e. corn) which produces tumors in the plant. The target cells of the plant are the germline cells, so the inserted DNA may be passed onto the progeny of the plant. In this example the plants progeny would not be killed by the application of atrazine. Other Uses Another use for the agrobacterium would be to give it atrazine resistance genes, and introduce it into the soil. In a study conducted by Devers et. al. the plasmid would be transferred both to plant roots and the rhizomes in the soil. This would give the plant resistance to atrazine taken up by its roots, but not sprayed on it. More importantly it would allow for an accelerated degredation of atrazine in the soil by soil microbes. This would be important in reducing the impact of pesticides on farm soil, especially if it could be replicated for more pesticides. References Agrobacterium. (2014, July 12). Retrieved December 9, 2014 from Wikipedia.org Devers, M., Henry, S., Hartmann, A., & Martin-Laurent, F. (2005). Horizontal gene transfer of atrazine-degrading genes (atz) from Agrobacterium tumefaciens St96-4 pADP1::Tn5 to bacteria of maize-cultivated soil.Pest Management Science,61(9), 870-880. Mateeva, T., Bogomaz, D., Pavlova, O., Nester, E., & Lutova, L. (2012). Horizontal Gene Transfer from Genus Agrobacterium to the Plant Linaria in Nature. Molecular Plant-Microbe Interactions,25(12), 1542-1551. Matveeva, Tatiana V., and Ludmila A. Lutova. "Horizontal Gene Transfer from Agrobacterium to Plants." Frontiers in Plant Science (2014). Print.